1. Field of the Invention
This invention relates to a battery-connecting plate, and more particularly to a battery-connecting plate for connecting an assembly of so-called rectangular batteries in series, the batteries, each with a positive and a negative electrodes at opposite end surfaces thereof, being juxtaposed with their positive and negative electrodes reversed in an alternating manner. The battery-connecting plate can connect the electrodes if there is a small difference in pitches between them, so as to facilitate the mounting of the battery-connecting plate to the batteries as well as its production.
2. Description of the Related Art
In recent years, an increasing number of electric vehicles and hybrid cars, which require a high-voltage, high-power source, have been produced as eco-friendly automobiles. For use with such automobiles, a technique has become important by which to gather a large number of small batteries in a downsized assembly.
FIG. 20 shows a conventional battery assembly 50 and a pair of front and rear battery-connecting plates 54, 55 which connect in series the positive and negative electrodes 52, 53 of the assembled rectangular batteries 51.
The rectangular batteries 51 each has the positive and negative electrodes 52, 53 in the form of a bolt (or nut) projecting at the front and rear end surfaces. The rectangular batteries 51 are held together, with their positive and negative electrodes 52, 53 reversed in an alternating manner, and wound around by a belt 56 to be fixed together.
The front battery-connecting plate 54, as shown in FIG. 21, includes a base plate 57 of synthetic resin, and one-hole busbars 58 and two-hole busbars 59 incorporated in a row arrangement in the base plate 57 by insert molding, the one-hole busbars 58 being located at the left and right ends of the base plate 57 and the two-hole busbars 59 therebetween. The "one-hole busbar" 58 herein means, as shown in FIG. 23B, a busbar provided with one electrode receiving hole 60 for passage therethrough of the above electrode 52 or 53, and the "two-hole busbar" 59 means, as shown in FIG. 23A, a busbar provided with two such holes 60. The battery-connecting plate 54 also includes an open/close cover 62 attached via hinges 61 to the upper edge of the base plate 57, which covers the base plate 57 after it is fixed with nuts 63 to the battery assembly 50 to prevent a short and the like. Denoted 64 is a resilient lock piece with a locking throughhole 64a and 65 is a corresponding lock projection.
The rear battery-connecting plate 55, as shown in FIG. 22, is of the same structure as the battery-connecting plate 54 except that it has no one-hole busbars 58, and includes a base plate 57' of synthetic resin, a row of two-hole busbars 59 incorporated in the base plate 57' by insert molding and an open/close cover 62' attached via hinges 61 to the upper edge of the base plate.
In the conventional battery assembly 50, the pitch A' between neighboring electrodes has greater tolerances toward the left and right ends of the battery assembly 50 due to a deviation in the width A between rectangular batteries 51 themselves combined with a deviation in centering the positive and negative electrodes 52, 53 on their respective batteries 51. Accordingly, with the battery-connecting plate 54, 55 of one-piece structure, its incorporated busbars 58, 59 tend to have their holes 60 deviated in position from their corresponding electrodes 52, 53, resulting in an awkward mounting of the battery-connecting plate 54, 55 to the battery assembly 50.
As a means of solving the above problem, there can be mentioned a method in which, as shown in FIG. 21, the hole 60 at one end of the front battery-connecting plate 54 is selected as a reference hole, and tolerances of the distances A', 2A', 3A' . . . nA' (n=13 in the illustrated example) from the reference hole to the holes 60 of each electrode 53, 52, 53 . . . are made as close as possible to improve the manufacturing dimensional accuracy. This, however, results in a cost increase.
As a second means, a method can be mentioned in which, as shown in FIGS. 23A and 23B, the diameter of the holes 60 of the two-hole and one-hole busbars 59, 58 is made sufficiently larger than the electrodes 52, 53. This, however, reduces the contact area with the electrodes 52, 53, possibly resulting in heat generation due to an increase in resistance and an unstable electrical connection.
As a third means, a method can be mentioned in which the rectangular batteries 51 themselves are produced with an improved accuracy in their width dimension A and the centering of their electrodes 52, 53 and their closer tolerances are maintained. This, however, also leads to a cost increase.